The present invention is directed to methods for making berry juice and more particularly, to methods of making juice from açaí berries.
Açaí berries are harvested from a palm tree (Euterpe oleracea Mart) that grows naturally near the Amazon river and its tributaries. The fruit of açaí berries is composed of a nut comprising about 80% of the berry volume, a layer of sclerid cells on the outer periphery of the nut, a matrix layer of lipids, fibers and other compounds outside the nut and a highly pigmented skin that is rich in anthocyanins. The berries are approximately 12 mm in diameter.
The berries degrade quickly once they are picked due to dehydration, bruising damage, microbiological activity, enzymatic activity and bio-chemical activities related to the high ambient temperatures of their environment which range from about 85° F. to about 102° F.). Degradation reduces the anthocyanin content in the skin of the berries.
The berries are traditionally hot soaked in nearby homes followed by a manual extraction of the outer two layers from the nut over a woven screen. This makes a thick pulp which is consumed locally within one day. Additionally, commercial açaí pulp is prepared using the two processes described below.
In a traditional batch process, Açaí is picked in the jungle and put into baskets called rasas. Rasas are carried at ambient temperature to a canoe or boat. The rasas are loaded into a larger boat and transported to an açaí market or directly to a processing plant. Total transport time at ambient temperature is between 2 and 48 hours.
At the processing plant, the açaí berries are soaked in water, normally at ambient temperature. The water may contain sodium hypochloride at a concentration of 100 ppm for up to 30 minutes. The berries are then soaked in hot water between 30 and 45 degrees Celsius for up to 4 hours. These warm berries are removed from the soak tank and processed in a rotating machine with water that rubs off the skin layer, the lipid layer and grains of lignin that are found between the lipid layer and the nut. This process makes a thick pulp that oxidizes rapidly, ferments quickly and contains a mixture of fat and water soluble fractions. The resulting pulp is measured to have a soluble solids level of less than 4 degrees brix. The pulp is sold fresh or pasteurized and/or frozen.
In a continuous process used today, açaí berries are picked in the jungle and put into rasas. The rasas are carried at ambient temperature to a canoe or boat. The rasas are then loaded into a larger boat and transported to an açaí market or directly to a processing plant. Total transport time at ambient temperature is between 2 and 48 hours.
At the processing plant, the açaí berries are soaked in hot water, normally at 40 to 60 degrees Celsius for 3 to 15 minutes. These warm berries are removed from the soak tank and processed in a rotating machine with water that rubs off the skin layer, the lipid layer and grains of lignin that are found between the lipid layer and the nut. This process also makes a thick pulp that oxidizes rapidly, ferments quickly and separates into fat and water soluble fractions quickly. The pH of this product is approximately 5.8 unless citric acid is added in the process to reduce the pH. The pulp is measured to have a soluble solids level of 3 to 4 degrees brix. The pulp is sold fresh or pasteurized and/or frozen.
There are numerous problems with pulp extracted by the existing processes. The pulp product contains “açaí sand” which is made of sclerid cells of lignin comprising up to 25% of the pulp by volume. These cells are extremely hard and abrasive. The abrasive nature of the cells damages processing equipment and prevents further processing through some homogenizers. The organoleptic impact of these cells has caused unpleasant mouth feel in many beverages blended with pulp containing açaí sand.
Additionally, the pulp product contains up to 50% lipids on a dry-weight basis. These lipids are mainly Omega-6 and Omega-9 fatty acids that are unstable. Rancidity in finished products is normal within 30 days of thawing and rancidity can occur within frozen drums of pulp. Despite extensive processing research, those skilled in the art have been unable remove the açaí sand or the lipids contained in the pulp product once the product has been processed without a significant negative impact on the flavor of the juice.
Additionally, the anthocyanin concentration found in the pulp is diluted by the presence of the water, lipids and the açaí sand. Moreover, the frozen pulp is difficult to thaw prior to use without lipid separation, rancidification or fermentation. Finally, it is very difficult to concentrate the pulp prior to packaging and shipping.
Therefore, a need exists for an improved juice from açaí berries and an improved method of making juice from açaí berries.